Characterization of glycans in the developmental stages of Myxobolus cerebralis (Myxozoa), the causative agent of whirling disease

Abstract

Glycans and sugar-binding molecules (lectins) form an interactive recognition system, which may enable parasitic organisms to adhere to host cells and migrate into target tissues. The aim of the present study was to analyse surface-associated glycans in the developmental stages of Myxobolus cerebralis (Hofer), the causative agent of whirling disease. A panel of biotin-labelled plant lectins was used to detect a broad spectrum of glycan motifs with high specificity. Binding sites were detected histochemically in the tissue sections of infected rainbow trout, Oncorhynchus mykiss (Walbaum), and infected Tubifex tubifex (Müller), and were characterized by light, fluorescence and transmission electron microscopy. With mannose-specific lectins [Lens culinaris agglutinin, Pisum sativum agglutinin, Canavalia ensiformis agglutinin (LCA, PSA, CanA)] mannose-containing glycans were detected in all the developmental stages and host tissues. No binding sites for galactose-specific lectins were present in M. cerebralis spores but reactivity with host tissues occurred. Diversity in glycans was detected by N-acetyl-D-galactosamine-specific lectins in sporoplasm cells of M. cerebralis and triactinomyxon spores. In the group of lectins with monosaccharide-specificity for N-acetyl-D-glucosamine (GlcNAc), the reactivity of Datura stramonium agglutinin (DSA), Lycopersicon esculentum agglutinin (LEA) and Solanum tuberosum agglutinin (STA) was restricted to polar capsules whereas Griffonia simplicifolia agglutinin II (GSA II) also bound to sporoplasm cells of stages in the fish host but not in those present in infected T. tubifex. Moreover, Triticum vulgaris (wheat germ) agglutinin (WGA) and succinylated WGA indicated the presence of N-acetyl-D-glucosamine polymers in polar capsules. No specificity for spores was observed concerning 'bisected'N-glycans and no reactivity in parasitic stages was observed with the fucose-binding lectin Ulex europaeus agglutinin (UEA) I, Sambucus nigra agglutinin (SNA) (specific for alpha2,6-sialylated glycans) and Maackia amurensis agglutinin (MAAI) (specific for alpha2,3-sialylated glycans). Arachis hypogaea (peanut) agglutinin (PNA), Erythrina cristagalli agglutinin (ECA), GSA I, Sophora japonica agglutinin (SJA), Dolichos biflorus agglutinin (DBA) and GSA II detected reactive sites solely confined to the developmental stages of M. cerebralis and were not reactive in the fish host. These parasite-specific glycans may play a role in the adhesion process of the parasite to fish epidermis prior to infection, but may provide protection to the host by activating the complement system, or stimulating an adaptive immune response as putative antigens.

Antigenic characterization of Enteromyxum leei (Myxozoa: Myxosporea)

“…The detected glycoproteic antigens of 15, 34 and 165 kDa of Enteromyxum leei contained Man/Glc moieties, which were the most abundant monosaccharides among the parasite's antigens, compared to the other monosaccharides tested. This result agrees with the ConA staining of E. leei proliferative and sporogonic stages observed by light and electron microscopy (Redondo & Álvarez-Pellitero 2009) and is a common trait among myxozoans (Muñoz et al 1999a, 2000b, Kaltner et al 2007, Redondo et al 2008. In fact, Man/ Glc moieties were present at the host−parasite interface in enteromyxoses (Redondo et al 2008, Redondo & Álvarez-Pellitero 2009.…”

“…The presence of chitin, a polymer of D-GlcNac, in polar capsules positive for WGA has been described for some myxozoans (Lukes et al 1993, Muñoz et al 1999a, 2000b, Kaltner et al 2007. Myxospore valves also contain substantial amounts of chitin (Lukes et al 1993, Muñoz et al 1999a).…”

“…In fact, Man/ Glc moieties were present at the host−parasite interface in enteromyxoses (Redondo et al 2008, Redondo & Álvarez-Pellitero 2009. The presence of surface Man moieties on offending microorganisms can trigger an innate immune response via complement system by the lectin pathway or via phagocytosis by Man-binding receptors on macrophages (Kaltner et al 2007). In fact, it is known that complement through the alternative pathway and macrophages through the respiratory burst activity are involved in (Cuesta et al 2006, Sitjà-Bobadilla et al 2006, Estensoro et al 2011.…”

Fish immune response to Myxozoan parasites

“…infections, the activity of the complement alternative pathway is initially increased and/or unaltered in response to the parasite exposure, but later on consumed to fight it (Cuesta et al, 2006a;. It has also been suggested that some parasite-specific glycans may activate the complement system through the lectin pathway (Kaltner et al, 2007). α-2M is a versatile anti-protease capable of trapping and functionally silencing all classes of microbial and parasite proteases.…”

Differences in viability and reactivity of actinospores of three myxozoan species upon ageing

“…Atkinson et al 2007, Kaltner et al 2007), molecular and morphological (e.g. Hallett et al 2004, Eszterbauer et al 2006, Holzer et al 2006, Székely et al 2007, as well as phylogenetic (e.g.…”